Composite structures of polypropylene (PP) and polar substrates are finding great utility in industry at the present time. One solution to the problem of securely adhering polypropylene to these polar substrates, like nylon, ethylene-vinyl alcohol copolymers (EVOH), polyvinyl alcohol polymers, metals, glass, or wood, etc., is to blend a polypropylene grafted with an unsaturated carboxylic acid or acid derivative with polypropylene and use this material directly as an adhesive layer between polypropylene and a polar substrate. It would sometimes be preferable to use polyethylene grafted with unsaturated carboxylic acid and acid derivatives because of ease in preparation relative to polypropylene graft copolymers.
If one blends the polyethylene graft copolymers with polypropylene, however, relatively poor adhesion is obtained to polar polymers and other polar substrates. In some instances no adhesion at all is obtained between the graft copolymer blend with polypropylene and the polar substrate. The blends of this invention overcome these difficulties.